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1. Evaluating the effectiveness of real-time closures for reducing susceptibility of small fish to capture

   https://doi.org/10.1093/icesjms/fsx152  

   Woods, Pamela J.; Elvarsson, Bjarki Þór; Sigurdsson, Thorsteinn; Stefánsson, Gunnar (August 2017, ICES Journal of Marine Science)

   Real-time spatial management in fisheries, a type of dynamic ocean management, uses nearly real-time data collection and dissemination to reduce susceptibility of certain species or age classes to being caught in mixed fisheries. However, as with many fisheries regulations, it is difficult to assess whether such a regulation can produce tangible results on population dynamics. In this study, we take advantage of a rare opportunity in which data regarding real-time closures (RTCs) are available for 1990–2014 alongside annual estimates of fishing mortality for three species (Atlantic cod, haddock, and herring) and catch for four species (all plus saithe) in Icelandic fisheries management. We use time series analyses to assess whether RTCs work as expected and yield a lower susceptibility of small fish to being caught, indicated by lower catch levels and selectivities (as estimated from fishing mortalities) in years with more closures. Results indicate that haddock and herring followed this pattern, but only under conditions of generally high fishing mortality. This study represents the first time evidence has been presented that real-time fishery closures can have a beneficial effect on population dynamics, but also suggests that results differ among species. 

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2. Dynamic human, oceanographic, and ecological factors mediate transboundary fishery overlap across the Pacific high seas

   https://doi.org/10.1111/faf.12791  

   Frawley, Timothy H; Muhling, Barbara; Brodie, Stephanie; Blondin, Hannah; Welch, Heather; Arostegui, Martin C; Bograd, Steven J; Braun, Camrin D; Cimino, Megan A; Farchadi, Nima; et al (January 2024, Fish and Fisheries)

   Abstract The management and conservation of tuna and other transboundary marine species have to date been limited by an incomplete understanding of the oceanographic, ecological and socioeconomic factors mediating fishery overlap and interactions, and how these factors vary across expansive, open ocean habitats. Despite advances in fisheries monitoring and biologging technology, few attempts have been made to conduct integrated ecological analyses at basin scales relevant to pelagic fisheries and the highly migratory species they target. Here, we use vessel tracking data, archival tags, observer records, and machine learning to examine inter‐ and intra‐annual variability in fisheries overlap (2013–2020) of five pelagic longline fishing fleets with North Pacific albacore tuna (Thunnus alalunga, Scombridae). Although progressive declines in catch and biomass have been observed over the past several decades, the North Pacific albacore is one of the only Pacific tuna stocks primarily targeted by pelagic longlines not currently listed as overfished or experiencing overfishing. We find that fishery overlap varies significantly across time and space as mediated by (1) differences in habitat preferences between juvenile and adult albacore; (2) variation of oceanographic features known to aggregate pelagic biomass; and (3) the different spatial niches targeted by shallow‐set and deep‐set longline fishing gear. These findings may have significant implications for stock assessment in this and other transboundary fishery systems, particularly the reliance on fishery‐dependent data to index abundance. Indeed, we argue that additional consideration of how overlap, catchability, and size selectivity parameters vary over time and space may be required to ensure the development of robust, equitable, and climate‐resilient harvest control rules. 

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3. Experimental demonstration of catch hyperstability from habitat aggregation, not effort sorting, in a recreational fishery

   https://doi.org/10.1139/cjfas-2019-0245  

   Dassow, Colin J.; Ross, Alexander J.; Jensen, Olaf P.; Sass, Greg G.; van Poorten, Brett T.; Solomon, Christopher T.; Jones, Stuart E. (April 2020, Canadian Journal of Fisheries and Aquatic Sciences)

   The relationship between angler catch rates and fish abundance can contribute to or hinder sustainable exploitation of fisheries depending on whether catch rates are proportional to fish abundance or are hyperstable. We performed a whole-ecosystem experiment in which fish abundance was manipulated and paired with weekly angler catch rate estimates from controlled experimental fishing. Catch rates were hyperstable (β = 0.47) in response to changes in fish abundance. By excluding effort sorting (i.e., catch rates remaining high because less skilled anglers leave the fishery as abundance declines), our experiment isolated the influence of fish aggregation as a driver of hyperstability. Spatial analysis of catch locations did not identify clustering around specific points, suggesting that loose aggregation to preferred habitat at the scale of the entire littoral zone was enough to maintain stable catch rates. In our study, general, non-spawning, habitat preferences created loose aggregations for anglers to target, which was sufficient to generate hyperstability. Habitat preferences are common to nearly all fishes and widely known to anglers, suggesting that many harvest-oriented recreational fisheries can be expected to exhibit hyperstability. 

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4. Environmental variability and fishing effects on the Pacific sardine fisheries in the Gulf of California

   https://doi.org/10.1139/cjfas-2020-0010  

   Giron-Nava, Alfredo; Ezcurra, Exequiel; Brias, Antoine; Velarde, Enriqueta; Deyle, Ethan; Cisneros-Montemayor, Andrés M.; Munch, Stephan B.; Sugihara, George; Aburto-Oropeza, Octavio (May 2021, Canadian Journal of Fisheries and Aquatic Sciences)

   null (Ed.)

   Small pelagic fish support some of the largest fisheries globally, yet there is an ongoing debate about the magnitude of the impacts of environmental processes and fishing activities on target species. We use a nonparametric, nonlinear approach to quantify these effects on the Pacific sardine (Sardinops sagax) in the Gulf of California. We show that the effect of fishing pressure and environmental variability are comparable. Furthermore, when predicting total catches, the best models account for both drivers. By using empirical dynamic programming with average environmental conditions, we calculated optimal policies to ensure long-term sustainable fisheries. The first policy, the equilibrium maximum sustainable yield, suggests that the fishery could sustain an annual catch of ∼2.16 × 10 5 tonnes. The second policy with dynamic optimal effort, reveals that the effort from 2 to 4 years ago impacts the current maximum sustainable effort. Consecutive years of high effort require a reduction to let the stock recover. Our work highlights a new framework that embraces the complex processes that drive fisheries population dynamics yet produces simple and robust advice to ensure long-term sustainable fisheries. 

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5. Participatory Risk Assessment of Humpback Whale (Megaptera novaeangliae) and Leatherback Turtle (Dermochelys coriacea) Bycatch in Northern Peru

   https://doi.org/10.3389/fmars.2021.776965  

   Costanza, Anna B.; Guidino, Chiara; Mangel, Jeffrey C.; Alfaro-Shigueto, Joanna; Verutes, Gregory; Caillat, Marjolaine; Samanta, Aritree; Hines, Ellen (December 2021, Frontiers in Marine Science)

   Uncertainties about the magnitude of bycatch in poorly assessed fisheries impede effective conservation management. In northern Peru, small-scale fisheries (SSF) bycatch negatively impacts marine megafauna populations and the livelihoods of fishers which is further elevated by the under-reporting of incidents. Within the last decade, accounts of entangled humpback whales (HBW) ( Megaptera novaeangliae ) off the northern coast of Peru have increased, while Eastern Pacific leatherback turtles (LBT) ( Dermochelys coriacea ) have seen over a 90% decline in nesting populations related in large part to bycatch mortality. By leveraging the experience and knowledge of local fishers, our research objectives were to use a low-cost public participation mapping approach to provide a spatio-temporal assessment of bycatch risk for HBW and LBT off two Peruvian fishing ports. We used an open-source, geographic information systems (GIS) model, the Bycatch Risk Assessment (ByRA), as our platform. Broadly, ByRA identifies high bycatch risk areas by estimating the intersection of fishing areas (i.e., stressors) with species habitat and evaluating the exposure and consequence of possible interaction between the two. ByRA outputs provided risk maps and gear risk percentages categorized as high, medium, and low for the study area and seven subzones for HBW in the austral winter and LBT in the austral summer. Overall, the highest bycatch risk for both species was identified within gillnet fisheries near the coast. Bycatch risk for most gear types decreased with distance from the coast. When we separated the ByRA model by port, our map outputs indicate that bycatch management should be port specific, following seasonal and spatial variations for HBW, and specific fishing gear impacts for HBW and LBT. Combined with direct bycatch mitigation techniques, ByRA can be a supportive and informative tool for addressing specific bycatch threats and marine megafauna conservation goals. ByRA supports a participatory framework offering rapid visual information via risk maps and replicable methods for areas with limited resources and data on fisheries and species habitat. 

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